The present invention relates to processes for producing amorphous or crystalline materials used for optical communication, lasers and other applications, and produced amorphous or crystalline materials.
Single-crystal or polycrystalline optical devices perform important roles in the fields of optical communication and lasers. Especially in optical communication, devices utilizing nonlinear characteristics of crystals are used for wavelength conversion and optical isolator. Nonlinear optical crystals are grown by various methods. Examples are; method (such as Czochralski method) of pulling a seed crystal up from a melt of a well-controlled composition, method (LPE) of inserting a substrate of matched lattice constants into a melt of a desired composition, and vapor phase growth method (such as MOCVD).
Amorphous material is superior in productivity to crystalline material. Examples are; quartz glass usable for fiber, optical glass usable for lens and amorphous film usable for reflection and wavelength selection. However, amorphous materials are low in nonlinearity, and hence inferior in properties as optical device, to crystalline materials.
It is an object of the present invention to provide a process or method of producing an amorphous material containing single crystal and/or polycrystal, and to provide an amorphous material containing single crystal and/or polycrystal.
The recent development in optical communication based mainly on fiber optics, and the advance in laser technique further increase the demand for functional optical devices with higher efficiency, smaller size, lower loss, lower noise, and ease of connection with fiber. However, crystals, though high in efficiency, are inferior in connectability with fiber and productivity, and costly. On the other hand, amorphous materials having good connectability and advantage in cost are problematical in efficiency.
Conventional crystal fabricating methods involve a complicated sequence of steps, such as crystal growth, cutting into pieces, optical polishing, alignment of optical axes, assemblage and inspection, eventually increasing the cost of production. Specifically, the growth rate (or velocity) of a single crystal is normally lower than a level of several mm/hr, and impeditive to the production efficiency. Furthermore, inspection of crystal orientation, optical surface polishing and other posterior steps are complicated and causative of cost increase. The conventional crystal or crystal device fabricating methods are not always adequate for supply of products in large quantity at low cost.
Amorphous material is suitable for mass production. However, amorphous material is inferior to crystals in performance and efficiency. For example, second order nonlinear characteristic used for wavelength conversion is unattainable from amorphous material.
Therefore, there is a demand for devices and materials which are advantageous in productivity like amorphous material, superior in performance and efficiency like crystalline material, and appropriate for connection with fiber.
As a result of investigation, the inventors of this application have found that it is possible to produce a single crystal, a polycrystal or an amorphous material containing a single crystal or polycrystal by irradiating pulse light to an amorphous base material (such as glass or amorphous film) of an appropriate composition and thereby forming a crystalline region selectively in an irradiated or light-condensed portion.
A production method according to the present invention is a method of producing an amorphous material containing at least one crystalline (monocrystalline or polycrystalline) region by irradiating pulse light to an original amorphous base material.